Now while it is indisputable that more and more the image acquisition devices are calling for sensors or gages the sizes and the weights of which are decreasing it is on the contrary in particular with the medical imagery systems relatively difficult to make use of illumination sources of small bulk and especially of low electrical power consumption.
The prior art made use of light sensors or gages which could either be monochromic or with colours. In the case of monochromatic sensors and with a purpose of taking coloured images, there has been carried out a trichromatic analysis from the primary colours obtained through mechanical switching of coloured filters in front of a white light source. In the case of colour sensors the white light was directly used. Now in the first case the mechanical switches exhibited inconveniences due to their consumptions, their bulks and their response times and in the second case the colour sensors offered lesser image definition and sensitivity.